Process of making superphosphates.



Toall wlmn itmay I 1T0 Drawing.

' sxusn'r'rn cUsa'rELLr,

or ra nan ro, f aunt;

PROCESS OF MAKING SUPERBHIO SIIHAEII'ES.

Be it known-that I, Grusur'rn CUSA'IELLI, doctor of chemistry, ofTa'ranto, Italy, have invented certain new and useful Improvements inProcesses of Making Superphosphates, and of which-the following is aspecification. I

The object of the present invention ,consists'of an improved processof'manufacture of superphosphates, which improves the quality of theproduct and renders its manufacture more economical, through theindustrial application of important reactive properties of nitric acidon the molecule of tricalcic phosphate and on the substances whichaccompany it in the phosphorites, in combination with the sulfuric acid.By addi a small quantity of nitric acid to th su furic acid necessary tothe treatment of phosphates and by rendering possible and phate, oneobtains superphosphates very superior hysically and chemically -to thoseobtained b acid alone.

The quantity of nitric acid necessary, ac-

' cording to the present invention for the action ma treatment ofphosphates may vary fro-m 1% to 5%, and more, for every hundred k110-grams of sulfuric acid at Baum, that is to say according to the qualityof the liosphate' under treatment. The best inustrial'results, however,are obtained by employing nitric acid at- 41-42 Baum, specific, gravity1400-1410, in .proportlons of from 3% to 4% of the quantity of sulfuricacid at 52-53 Baum, specific gravity hitherto required for the treatmentof 100 kilograms of phosphate.

The nitrous vapors resulting'from the reif necessary be recovered; theemployed may also be partially Consequently the nitric acid nitric acirecovered.

employed in the treatment of phosphates has the property of eliminatingevery trace of insoluble basic phosphates, thus rendering the productsimilar, physically and chemically, to bone superphosphatebecausecontaining nitrogen also; there is thus obtained an industrially andcommercially superior superphosphate since it is more easily decomposed,dried and pulverized. It is, moreov'er-,more economical sinceit-requires less sulfuric acid, since even only Specification of LettersPatent. Application filed July 6, 1910. Serial No. 570,593.

y'the reaction with the sulfuric Patented Jilly-'18, 19h.

be treated, thus economizing in the grind ing, since superphosphates areobtained which contain more soluble-phosphoric anhydrid, which canbesold-immediately after manufacture and which are-much more valuable anduseful to agriculture since they have greater fertilizing value andaremore easily assimilated and contain less free acid than the normal.Superphosphatesthus obtained can never be liableyas are the. or-

slightlypulverized phosphates may easily dinary superphosphates, toundergo ret-rogression; on the contrary. the monobasic phosphates(superphosphatesyobtained by my process are more pulverulent and drier,and contain a .greater quantity of phosphoric anhydrid soluble only inwater than the ordinary phosphates. When placed in' the soil they havethe property of spreading rapidly therein by appropriating to themselvesthe bases thereof, by being horriogeneously converted into bibasicphosphates, that is to say into the condition for prompt allid e w yabsorption and assimilation by the pant. My new process of treatmenteliminates certain difiic'ulties of roduction, and economizes insulfuric acid, whether phosphates rich in carbonate of lime, or in thosewhich contain less quantities are used; it-greatly accelerates theaction of sulfuric acid on the tribasic phosphate in phosphates poor incarbonate of lime, as' well'as inthose which are almost totally lackingin it. No matter with what phosphate'one is working, the resultingproduct is a very-spongy superphospha-te, easily decomposed and'dried,and having all the qualities'already mentioned. By employing nitric acidthere is obtained an excellent superphosphate from a phosphatepulverized less than that hitherto employed, thus effecting aconsiderable economy intime and expense by grinding the phosphate withmetal screens with slightly serrated plate s. Another advantage-istherefore obtained, that isless dust is produced in milling, a muchgreater efiiciency of the mills being thus obtained than hitherto. Itshould also be noted that immediately after having finished thetreatment of the phosphate, the superphosphate obtained gives unit moreofphosphoric anhydrid soluble in water and of citrate of ammonium foreach kilogram of superphosphates than could be obtained heretofore; andif it lies unused for a long time,

the yield of soluble phosphoric anhydrids in superphosphates, in placeof diminishing,

grated and dried; it has the considerable advantage ofcompletelyavoidingthe very grave inconvenience of nodules in the superphosphate itself.

I claim: v

' An improvement in the process of mania facture of superphosphates bymeans of the practical applicationof the reactiveproperties of nitr cacid on phosphates mixed with sulfuric acid, said process consistinginemanhydrid, easily decomposable, more pulverulent and drier, richer infertilizing material," more easily assimilated by: plants thansuperphosphates made by methods now in use, and also more economical.

-In testimony whereof I have afiixed my signature in presence of twowitnesses.

GIUSEPPE GUSATELLI.

Vitnessesz- DUILIO Nannom, I 1 GIOVANNI 'BOR'TQLUZZI'.

